And [recall] when We made an appointment with Moses for forty nights. (2:51)

Almuntakhab Fi Tafsir Alquran Alkarim

Then We ordained the divine assignation for Mussa and arranged the place and the time where and when We would be exposed to his mental view and he was in audience of Us after the completion of exclusive religious devotion for fourty nights, and you became impatient and paid reverence and veneration to the calf which you regarded it as a godhead, characterizing yourselves by perversity of judgment and wrong actions

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(2:51) Call to mind that when We invited Moses for a fixed term of forty nights and days, *67 you took to calf worship in his absence. *68 Though you had committed a wicked transgression,

And [recall] when We made an appointment with Moses for forty nights. meaning

*67). When the Israelites reached the Sinai peninsula after their exodus from Egypt, God summoned Moses to the mountain for forty days and nights so that the nation which had now achieved independence could be taught law and morality. (See Exodus 24-3l.)
*68). The cult of cow-worship was widespread among Israel's neighbours. It was particularly common in Egypt and Canaan. After the time of Joseph, when the Israelites fell prey to degeneracy and became the slaves of the Copts, they were contaminated by many of the corrupt practices prevalent among their rulers. Cow-worship was one of them. (There is a detailed account of the episode of calf-worship in Exodus 32.)
 

And [recall] when We made an appointment with Moses for forty nights. meaning in Urdu

یاد کرو، جب ہم نے موسیٰؑ کو چالیس شبانہ روز کی قرارداد پر بلایا، تو اس کے پیچھے تم بچھڑے کو اپنا معبود بنا بیٹھے اُس وقت تم نے بڑی زیادتی کی تھی